You can use an iCustom call to find the dots if the indicator uses buffers.
Looking at that image I am almost certain that it is a repainting indicator so you may find that you cannot get an alert when the dot happens
You want to know if a dot exists on a specific bar. Just get the value of the indicator, (one of two buffers,) and see if it is EMPTY_VALUE or not.
You should write a self documenting function instead of calling iCustom
Detailed explanation of iCustom -
1) I have said: "the indicator in the figure is only for an example".2) Here you are the screen with dot and without
As WHRoeder has said, some indicators do not place any value in the buffer for the current bar. In such cases you will not get any value returned for